FIGURE 1.

Dietary heme iron intake and fecundability among women planning a pregnancy in the Snart Foraeldre (A) and PRESTO (B) studies, fitted with the use of restricted cubic splines. The reference level is the lowest value in each cohort (0.01 for both). There are 3 knots located at the 10th, 50th, and 95th percentiles of the distribution. The line indicates the FR and the shaded area indicates the 95% CI. The spline is trimmed at the 99th percentile. Splines are adjusted for age, vocational training/education, BMI, physical activity, smoking, alcohol consumption, use of oral contraceptives, parity, cycle regularity and length, doing something to improve chances of conception, use of iron and vitamin C supplements, multivitamin use, dietary vitamin C (continuous), and total energy (continuous). The PRESTO models are also adjusted for race/ethnicity. FR, fecundability ratio.